Inflammation normally is a localized, protective response to trauma or microbial invasion that destroys, dilutes, or walls-off the injurious agent and the injured tissue. It is characterized in the acute form by the classic signs of pain, heat, redness, swelling, and loss of function. Microscopically, it involves a complex series of events, including dilation of arterioles, capillaries, and venules, with increased permeability and blood flow, exudation of fluids, including plasma proteins, and leukocyte migration into the area of inflammation.
Diseases characterized by inflammation are significant causes of morbidity and mortality in humans. Commonly, inflammation occurs as a defensive response to invasion of the host by foreign, particularly microbial, material. Responses to mechanical trauma, toxins, and neoplasia also may results in inflammatory reactions. The accumulation and subsequent activation of leukocytes are central events in the pathogenesis of most forms of inflammation. Deficiencies of inflammation compromise the host. Excessive inflammation caused by abnormal recognition of host tissue as foreign or prolongation of the inflammatory process may lead to inflammatory diseases as diverse as diabetes, arteriosclerosis, cataracts, reperfusion injury, and cancer, to post-infectious syndromes such as in infectious meningitis, rheumatic fever, and to rheumatic diseases such as systemic lupus erythematosus and rheumatoid arthritis. The centrality of the inflammatory response in these varied disease processes makes its regulation a major element in the prevention control or cure of human disease.
An important cytokine in the inflammatory process is interleukin-8 (IL-8). IL-8 is a chemokine. It was identified as an agonist for neutrophils on the basis of two effects, chemotaxis and the release of granule enzymes. IL-8 binds to two receptors on neutrophils. IL-8 receptors are also found on monocytes, basophils, and eosinophils. In human fibroblasts, cytomegalovirus has been shown to induce the expression of IL-8 receptors and to replicate more rapidly when cells are exposed to IL-8. IL-8 is a potent chemoattractant for neutrophils; and the early stages of periodontal disease are characterized by the influx of neutrophils. IL-8 is a potent inducer of angiogenesis in several angiogenesis-dependent chronic inflammatory conditions, including rheumatoid arthritis, psoriasis, and idiopathic pulmonary fibrosis. Additionally, IL-8 is an important source of angiogenic activity in human lung cancer. Also, IL-8 expression correlates with experimental metastatic activity of some melanoma cell lines. Thus, an effective method to treat inflammatory diseases would be to administer an agent that would inhibit IL-8.